U.S. patent number 8,837,043 [Application Number 12/796,253] was granted by the patent office on 2014-09-16 for light source arrangement for an illumination device of a medical-optical observation apparatus.
This patent grant is currently assigned to Carl Zeiss Meditec AG. The grantee listed for this patent is Markus Bausewein, Christian Luecke, Peter Reimer. Invention is credited to Markus Bausewein, Christian Luecke, Peter Reimer.
United States Patent |
8,837,043 |
Luecke , et al. |
September 16, 2014 |
Light source arrangement for an illumination device of a
medical-optical observation apparatus
Abstract
A light source arrangement (101) for an illumination device of a
medical-optical observation apparatus has an illumination light
source (7) and an illumination optical unit (15) for illuminating
an observation object (23) with illumination light from the
illumination light source (7). The light source arrangement (101)
has at least one luminescence emitter (3) as light source and an
imaging optical unit (105) that generates an image (7) of the at
least one luminescence emitter (3) with a defined magnification
scale, which image forms the illumination light source for the
illumination device.
Inventors: |
Luecke; Christian (Oberkochen,
DE), Bausewein; Markus (Aalen, DE), Reimer;
Peter (Ellwangen, DE) |
Applicant: |
Name |
City |
State |
Country |
Type |
Luecke; Christian
Bausewein; Markus
Reimer; Peter |
Oberkochen
Aalen
Ellwangen |
N/A
N/A
N/A |
DE
DE
DE |
|
|
Assignee: |
Carl Zeiss Meditec AG
(DE)
|
Family
ID: |
42712448 |
Appl.
No.: |
12/796,253 |
Filed: |
June 8, 2010 |
Prior Publication Data
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Document
Identifier |
Publication Date |
|
US 20100309549 A1 |
Dec 9, 2010 |
|
Foreign Application Priority Data
|
|
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|
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Jun 9, 2009 [DE] |
|
|
10 2009 024 942 |
|
Current U.S.
Class: |
359/385;
359/432 |
Current CPC
Class: |
G02B
21/082 (20130101); G02B 21/0012 (20130101); G02B
21/025 (20130101); A61B 2090/309 (20160201); G02B
21/22 (20130101); A61B 1/06 (20130101) |
Current International
Class: |
G02B
21/06 (20060101) |
Field of
Search: |
;359/385,432,386-390 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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16004 |
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Apr 1914 |
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DE |
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196 38 263 |
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Apr 1998 |
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DE |
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20 2004 019 849 |
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Mar 2005 |
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DE |
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2004 019 849 |
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Mar 2005 |
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DE |
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103 47 732 |
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May 2005 |
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DE |
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699 19 902 |
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Sep 2005 |
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DE |
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10 2005 032 501 |
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Mar 2006 |
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DE |
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10 2006 013 761 |
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Sep 2007 |
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DE |
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102006047724 |
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Feb 2008 |
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DE |
|
10 2007 041 003 |
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Dec 2008 |
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DE |
|
10 2007 041 439 |
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Mar 2009 |
|
DE |
|
0 661 020 |
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Jul 1995 |
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EP |
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01164351 |
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Jun 1989 |
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JP |
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2002010978 |
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Jan 2002 |
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JP |
|
Primary Examiner: Font; Frank
Attorney, Agent or Firm: Hespos; Gerald E. Porco; Michael J.
Hespos; Matthew T.
Claims
What is claimed is:
1. An illumination device for medical-optical observation apparatus
comprising: an illumination optical unit with a collector optical
unit (17, 217) forming an entry end for receiving light from an
illumination light source, a condenser optical unit (19, 219)
forming an exit end for illuminating an observation object (23)
with illumination light from the illumination light source (7, 207)
and an aperture diaphragm (29, 229) located between the collector
optical unit (17, 217) and the condenser optical unit (19, 219);
and at least one light source arrangement (101, 201) having at
least one luminescence emitter (3, 203) as primary light source and
an imaging optical unit (5, 105, 205) wherein the light source
arrangement (101, 201) is located in front of the collector optical
unit (17, 217) of the illumination optical unit such that the
imaging optical unit (5, 105, 205) of the light source arrangement
(101, 201) generates an image (7, 207) of the at least one
luminescence emitter (3, 203) with a defined magnification scale at
a distance from the aperture diaphragm (29, 229) and between the
imaging optical unit (5, 105, 205) of the light source arrangement
(101, 201) and the collector optical unit (17, 217) of the
illumination optical unit, and wherein the image (7, 207) with the
defined magnification scale forms the illumination light source for
the illumination optical unit.
2. The illumination device of claim 1, wherein the imaging optical
unit is a double collector (105, 205).
3. The illumination device of claim 1, wherein the imaging optical
unit (5, 105, 205) has at least one aspherical lens.
4. The illumination device of claim 1, wherein the imaging optical
unit (5, 105, 205) comprises an achromatic or apochromatic
lens.
5. The illumination device of claim 1, wherein the luminescence
emitter emits broadband light.
6. The illumination device of claim 1, wherein the luminescence
emitter (3, 203) emits narrowband light.
7. The illumination device of claim 6, further comprising a
converter element (111), with a converter phosphor for converting
at least part of the narrowband light of the luminescence emitter
(3) and introducing the narrow band light into the light source
arrangement (101) between the at least one luminescence emitter (3)
and the image (7) of the at least one luminescence emitter (3).
8. The illumination device of claim 7, wherein the converter
element (111) is introduced into the light source arrangement (101)
between the imaging optical unit and the image (7) of the at least
one luminescence emitter (3).
9. The illumination device of claim 7, wherein the at least one
converter element (111) has an entrance surface for the light
emerging from the luminescence emitter (3), the entrance surface
facing the luminescence emitter (3) and being provided with a
dichroic layer that is transparent to light entering into the
converter element (111) and having a wavelength distribution of the
light emitted by the luminescence emitter (3) and is highly
reflective to converted light directed in a direction of the
luminescence emitter (3).
10. The illumination device of claim 1, wherein the image (7, 207)
of the at least one luminescence emitter (3, 203) is formed with a
magnification scale in the range of between 1.5.times. and
2.5.times..
11. The illumination device of claim 1, wherein the at least one
illumination light source comprises at least two illumination light
sources (7A, 7B) and both illumination light sources are formed by
the same light source arrangement (201).
12. The illumination device of claim 1, wherein the at least one
illumination light source comprises at least two illumination light
sources (7A, 7B) and each illumination light source (7A, 7B) is
formed by a dedicated light source arrangement (201A, 201B).
13. A medical-optical observation apparatus comprising the
illumination device of claim 1.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a light source arrangement for an
illumination device of a medical-optical observation apparatus,
which illumination device has an illumination light source and an
illumination optical unit for illuminating an observation object
with illumination light from the illumination light source. The
invention additionally relates to an illumination device for a
medical-optical observation apparatus, and such a medical-optical
observation apparatus.
2. Description of the Related Art
An illumination device for a surgical microscope, embodied as an
ophthalmological surgical microscope, is described for example in
DE 10 2007 041 003 A1, wherein the illumination systems in the
surgical microscope are supplied from a halogen or xenon light
source via spliced optical waveguides. This means, however, that
the illumination types of coaxial illumination and surrounding
illumination cannot be regulated independently of one another. In
the case where a plurality of optical waveguides are used, although
separate regulation is possible in principle, this increases the
complexity of the illumination system.
DE 20 2004 019 849 U1 and EP 0 661 020 A1 additionally disclose
illumination devices which provide separate light sources for red
reflection illumination and surrounding illumination. DE 20 2004
019 849 U1 additionally mentions that light emitting diodes can be
used as the light source. However, no further explanation is given
regarding the practical configuration of the illumination device
when using light emitting diodes as light sources.
It is an object of the present invention to provide an advantageous
light source arrangement for an illumination device of a
medical-optical observation apparatus. It is a further object of
the present invention to provide an advantageous illumination
device for a medical-optical observation apparatus. Finally, it is
an object of the present invention to provide an advantageous
medical-optical observation apparatus.
SUMMARY OF THE INVENTION
The invention provides a light source arrangement for an
illumination device of a medical-optical observation apparatus, the
illumination device having an illumination light source and an
illumination optical unit for illuminating an observation object
with illumination light from the illumination light source. The
light source arrangement comprises at least luminescence emitters
as primary light source for the illumination device. The light
source arrangement furthermore comprises an imaging optical unit,
which generates an image, in particular a real image, of the at
least one luminescence emitter with a defined magnification scale.
The image constitutes the illumination light source for the
illumination device. In the simplest case, a converging lens can be
employed as imaging optical unit. However, more complex optical
units can preferably be used as well.
The present invention is based on the insight that, in illumination
devices for medical-optical observation apparatuses, the light
sources used heretofore, such as exit ends of optical fibers,
incandescent lamps or gas discharge lamps, cannot be replaced by a
light emitting diode without either bringing about a loss in
quality of the illumination or adapting the illumination optical
unit of the illumination device to the new light source. By way of
example, in the case of an illumination device having the exit end
of an optical fiber as illumination light source, the replacement
of the exit end by a light emitting diode would lead, on account of
the different emission characteristics, to a significant reduction
of the quantity of illumination light transmitted via the
illumination optical unit if the illumination optical unit were not
adapted to the new light source. However, since a light emitting
diode has a significantly larger emission angle than the exit end
of an optical fiber, the illumination optical unit would have to be
configured with a larger numerical entrance aperture, which would
enlarge the optical components in terms of their diameter. Such
enlargement means more structural space, however, which would make
the illumination device more bulky. Moreover, it is not readily
possible to replace the optical components in existing illumination
devices. According to the invention, therefore, the light emitting
diode itself is not used as the illumination light source, rather
an image of the illumination light source is used, which image is
generated by means of an imaging optical unit with a defined
magnification scale. The image of the at least one luminescence
emitter can thus be optimally adapted to the illumination optical
unit of the illumination device.
In the abovementioned example with the exit end of an optical fiber
and the LED, the following conditions are present: the emission
angle of an optical fiber is approximately .+-.34.degree.. By
contrast, the emission angle of a light emitting diode, which is a
luminescence emitter that is particularly suitable as a light
source, is .+-.60.degree., that is to say almost double that of the
optical fiber. However, the illumination optical unit of the
illumination device is adapted to the transmission of illumination
light with an aperture angle such as is offered by the optical
fiber. In the light source arrangement according to the invention,
then, the imaging optical unit can be designed in such a way that
the imaging scale of the image of the light emitting diode is
approximately 2.times.. As a result, the luminous area of the image
is increased by a factor of 2 by comparison with the original light
emitting diode, and at the same time the emission angle is reduced
by a factor of 2. Therefore, the emission angle is approximately
.+-.30.degree., which approximately corresponds to the emission
angle of an optical fiber. In this case, the luminous area of the
light emitting diode can be chosen such that the image of the
luminous area magnified by a factor of 2 corresponds approximately
to the luminous area of the exit end of an optical fiber. If the
light source arrangement according to the invention is then
arranged in relation to the illumination device such that the image
of the light emitting diode enlarged by a factor of 2 is situated
where the exit end of the optical fiber would otherwise be
situated, the light of the light emitting diode, that is to say the
light of the image thereof, can be coupled into the illumination
optical unit adapted to the optical fiber just as well as the light
from the optical fiber itself. The adaptation to the emission
characteristic of an incandescent lamp or of a gas discharge lamp
can also be effected in a similar manner. The light source
arrangement according to the invention can therefore be used with
existing illumination devices without an adaptation to the new
light source having to be performed in the case of said existing
illumination devices.
A double collector can advantageously be employed as the imaging
optical unit. Such a double collector affords the possibility that
a parallel beam path is present between the two lenses of the
double collector. In this way, the image of the at least one
luminescence emitter can be generated at any desired distance from
the luminescence emitter. With the use of light-directing elements
such as, for instance, mirrors or prisms, great freedom then arises
in the positioning of the at least one luminescence emitter. The
latter can therefore also be arranged at a greater distance from
the illumination device. Moreover, a total of at least four lens
surfaces are then available, which can be chosen in a suitable
manner for producing an optimized imaging quality.
In one development of the invention, the imaging optical unit of
the light source arrangement has at least one aspherical lens,
which can be advantageous with regard to the correction of imaging
aberrations, particularly with regard to the correction of a
spherical aberration. Moreover, the imaging optical unit can
comprise an achromatic or apochromatic lens in order that chromatic
aberrations in the imaging of the luminescence emitter are kept
small. This is advantageous, in particular, if a luminescence
emitter that emits broadband light such as, for instance, a white
light emitting diode is employed. Instead of a luminescence emitter
that emits broadband light, however, it is also possible to employ
a luminescence emitter that emits narrowband light, for example if
illumination in a narrow spectral range is intended to be effected.
However, a luminescence emitter that emits narrowband light can
also be employed if the illumination of an observation object with
broadband light is intended to be effected. In this case, the light
source arrangement comprises a converter element, that is to say an
independent part not integrated into the luminescence emitter,
which converter element is provided with a converter phosphor for
converting at least part of the narrowband light of the
luminescence emitter. In that case the converter element is
introduced or can be introduced into the light source arrangement
between the at least one luminescence emitter and the image of the
at least one luminescence emitter, for example between the imaging
optical unit and the image of the at least one luminescence
emitter. In such a configuration of the light source arrangement,
by exchanging the converter element for a converter element having
a different converter phosphor, it is possible to alter the
spectral characteristic of the image of the light source, for
example in order to provide light having a specific color
temperature.
The converter element can have an entrance surface for the light
emerging from the luminescence emitter, which entrance surface
faces the luminescence emitter and is provided with a dichroic
layer that is transparent to light entering into the converter
element and having the wavelength distribution of the light emitted
by the luminescence emitter. By contrast, said dichroic layer is
highly reflective to converted light directed in the direction of
the luminescence emitter. In this way, it is possible to prevent
converted light from emerging from the converter element in the
direction of the luminescence emitter and thus being lost for the
illumination.
An illumination device according to the invention for a
medical-optical observation apparatus is equipped with at least one
light source arrangement according to the invention. The use of a
light source arrangement according to the invention with a
luminescence emitter, for instance an LED, as primary light source
affords a considerable price advantage, and additionally a longer
service life, compared with the use of halogen and xenon lamps. In
comparison with the use of an optical fiber as a light source,
light emitting diodes, in particular, afford the advantage of more
homogeneous light propagation.
If the illumination device has at least two illumination light
sources, the latter can be formed, in particular, by the same light
source arrangement. In other words, the light source arrangement
then comprises at least two luminescence emitters that are imaged
by means of the same imaging optical unit. As an alternative,
however, there is also the possibility of using two separate light
source arrangements as illumination light sources. In other words,
at least two light source arrangements each having a dedicated
luminescence emitter and a dedicated imaging optical unit can be
employed.
A medical-optical observation apparatus according to the invention,
which can be embodied for example as an endoscope or in particular
as a surgical microscope, is equipped with an illumination device
according to the invention. The advantages that can be obtained in
this case are apparent from the advantages that have already been
described with regard to the illumination device according to the
invention and with regard to the light source arrangement according
to the invention.
Further features, properties and advantages of the invention will
become apparent from the following description of exemplary
embodiments with reference to the accompanying figures.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a first exemplary embodiment of a light source device
according to the invention.
FIG. 2 shows a second exemplary embodiment of a light source device
according to the invention.
FIG. 3 shows a third exemplary embodiment of a light source device
according to the invention.
FIG. 4 shows a first exemplary embodiment of a medical-optical
observation apparatus comprising an illumination device according
to the invention.
FIG. 5 shows a second exemplary embodiment of a medical-optical
observation apparatus comprising an illumination device according
to the invention.
FIG. 6 shows a third exemplary embodiment of a medical-optical
observation apparatus comprising an illumination device according
to the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
A first exemplary embodiment of a light source arrangement
according to the invention is described below with reference to
FIG. 1. The figure shows the simplest construction of the light
source arrangement 1 according to the invention, comprising merely
a luminescence emitter, a light emitting diode 3 in the present
exemplary embodiment, as primary light source and a converging lens
5. The converging lens 5 constitutes the imaging optical unit of
the light source arrangement, with the aid of which a real image 7
of the light emitting diode 3 is generated. The optical parameters
of the converging lens 5, that is to say its refractive index and
the curvatures of the lens surfaces are chosen such that the
magnification scale of the image 7 in comparison with the light
emitting diode 3 as the original image lies between 1.5 and 2.5,
and in particular between 2 and 2.5. This has the effect that the
luminous area of the image 7 is 1.5 times to 2.5 times as large as
the luminous area of the light emitting diode 3, and in particular
2 times to 2.5 times as large. In the present exemplary embodiment,
the magnification scale is 2, that is to say the aperture angle
.alpha. of the radiation beam emitted by the light emitting diode 3
is twice as large as the aperture angle .alpha.' of the radiation
beam emerging from the image 7. In addition, the luminous area of
the image 7 is twice as large as the luminous area of the light
emitting diode 3.
If it is assumed that a light emitting diode emits with an aperture
angle of around .+-.60.degree., the aperture angle .alpha.' with
which the image 7 of the light emitting diode emits is
.+-.30.degree., which corresponds approximately to the emission
angle of the exit end of an optical fiber. In the case of a light
source arrangement having a magnification scale of approximately 2,
therefore, the image 7 of the light emitting diode 3 can be
arranged instead of the exit end of an optical fiber in an
illumination device for a medical-optical observation
apparatus.
A second exemplary embodiment of the light source arrangement
according to the invention is illustrated in FIG. 2. Elements which
do not differ from the first exemplary embodiment are designated by
the same reference signs as in FIG. 1 and will not be explained
again.
The light source arrangement in accordance with the second
exemplary embodiment illustrated in FIG. 2 differs from the light
source arrangement illustrated in FIG. 1 in that the imaging
optical unit 105 is embodied in the form of a double collector
having two converging lens 107, 109. The imaging optical unit 105
generates an image 7 of the light emitting diode 3 with an imaging
scale of approximately two. However, other imaging scales, in
particular imaging scales between 1.5 and 2.5, and in particular
between 2 and 2.5 are also possible.
The lenses of the double collector 105, which are illustrated only
schematically in FIG. 2, can be double-convex and/or planoconvex
lenses having spherical and/or aspherical lens surfaces. The lens
107 of the double collector that is situated on the light emitting
diode side is configured such that it images the light emitting
diode 3 toward infinity, that is to say generates a parallel
radiation beam. The latter is in turn focused by the lens 109
situated on the image side, in order to generate the image 7 of the
light emitting diode 3.
Since a parallel radiation beam is present between the two lenses
107, 109 of the double collector, the distance between the two
lenses 107, 109 can be varied and afocal optical elements, for
example mirrors or prisms for deflecting the radiation beam, can
additionally be arranged therebetween. Great freedom between the
arrangement of the light emitting diode 3 as luminescence emitter
and the image 7 of the light emitting diode 3 is achieved in this
way.
In the first exemplary embodiment as also in the second exemplary
embodiment, white light emitting diodes are employed as broadband
luminescence emitters. However, there is also the possibility of
using narrowband luminescence emitters, for example blue or red
light emitting diodes, instead of broadband luminescence emitters.
Depending on the medical-optical apparatus for which the light
source arrangement is intended to be used, it is also possible to
use luminescence emitters which emit in the non-visible spectral
range, for example light emitting diodes which emit in the
ultraviolet or infrared spectral range. This can be expedient, for
instance, if fluorescence is intended to be excited in the
observation object by means of the light source arrangement.
However, even if the observation object is intended to be
illuminated with white illumination light, it is possible to employ
a narrowband luminescence emitter, for example a blue light
emitting diode or a light emitting diode which emits in the
ultraviolet spectral range. In order nevertheless to be able to
provide broadband illumination light, in particular white
illumination light, the light source arrangement is then equipped
with a converter element, which converts at least part of the light
emitted by the light emitting diode into light having a longer
wavelength.
A light source arrangement comprising a converter element is
illustrated in FIG. 3. The basic construction of the light source
arrangement illustrated in FIG. 3 corresponds to that of the light
source arrangement illustrated in FIG. 2. There is just a converter
element 111 arranged between the two converging lenses 107, 109 of
the double collector 105. In principle, however, the converter
element 111 can also be arranged between the light emitting diode 3
and the lens 107 on the light emitting diode side, or between the
lens 109 on the image side and the image 7, as is indicated by the
reference signs 111' and 111'' in FIG. 3. In the last-mentioned
case, in particular, it is possible to avoid chromatic aberrations
even without achromatic or apochromatic lenses since the imaging
optical unit 105 is only permeated by a narrow wavelength
distribution.
The converter element 111 is equipped with a converter phosphor
that converts at least a portion of the narrowband light from the
light emitting diode 3 into light having a longer wavelength. If
the light emitting diode 3 emits blue light, for example, the
converter phosphor can be chosen such that it converts part of the
blue light into yellow light, such that the superimposition of the
yellow light with the remaining blue light produces white light. By
contrast, if a light emitting diode which emits UV radiation is
used, for example, it is possible to convert the UV radiation
completely into light in the visible spectral range by means of the
converter phosphor. In addition, it is possible by using a
plurality of converter elements which are introduced or can be
introduced one behind another in the light source arrangement and
have different converter phosphors, or by means of one converter
element comprising a converter phosphor mixture, to convert the UV
radiation completely into light having at least two wavelength
distributions that in total result in the broadband or white light.
However, the use of converter elements which are arranged in the
light source arrangement or can be introduced into the light source
arrangement one behind another or of one converter element which is
arranged in the light source arrangement or can be introduced into
the light source arrangement with a phosphor mixture is possible,
in principle, not only with the use of an LED which emits in the UV
range, but also with the use of an LED which emits in the visible
spectral range.
Particularly if the converter element or the converter elements of
the light source arrangement is or are configured in exchangeable
fashion, the spectral wavelength distribution of the light emitted
by the image 7 can be set in wide ranges, for example in order to
be able to realize white light having different color temperatures
and/or light having white and non-white wave distributions.
In order to increase the efficiency of the converter element z the
latter can be provided with a dichroic layer at its surface facing
the light emitting diode, said dichroic layer being transmissive to
the light from the light emitting diode but highly effective for
converted light.
A surgical microscope as an example of a medical-optical
observation apparatus having an illumination device which comprises
a light source arrangement according to the invention is
illustrated in a schematic side view in FIG. 4. Besides a light
source arrangement 101 according to the invention, the construction
of which substantially corresponds to that of the light source
arrangement described in FIG. 2, the figure shows the main
objective 13 of the surgical microscope and also an illumination
optical unit 15, which comprises a collector optical unit 17 and a
condenser optical unit 19. In the present exemplary embodiment,
both the collector optical unit 17 and the condenser optical unit
19 are constructed from lens groups in order to reduce imaging
aberrations in the illumination beam path as far as possible. By
means of a beam splitter, for example a partly transmissive mirror
21, the illumination beam path is coupled into the main objective
13 and fed to the observation object 23 via the main objective.
The light source device 101 comprises aspherical lens surfaces in
FIG. 4 in order to minimize imaging aberrations in the image 7 of
the light emitting diode 3.
Besides the illumination beam path comprising the optical elements
of collector 17, condenser 19, beam splitter 21 and main objective
13, the surgical microscope has an observation beam path. The
latter, proceeding from the observation object 23, runs through the
main objective 13 and the beam splitter 21, wherein the observation
beam path, in contrast to the illumination beam path, is not
deflected by the beam splitter 21. In the observation beam path,
the beam splitter 21 is followed by a magnification setting element
25, by means of which the magnification factor with which a
magnification is effected in the observation beam path can be set.
The magnification setting element 25 can be embodied, in
particular, as a zoom system containing at least three lenses or
lens groups, wherein two lenses or lens groups can be displaced
along the optical axis, such that the magnification factor can be
set in a continuously variable fashion. As an alternative, it is
also possible for the magnification setting element 25 to be
configured as a stepped magnification changer. An element of the
latter type contains a plurality of lens groups, wherein the lenses
of a lens group are in a fixedly predefined arrangement with
respect to one another. In such a stepped magnification changer,
the magnification factor is changed by different lens groups of
this type being alternately introduced into the observation beam
path.
The magnification setting unit 25 can already be embodied as a
two-channel optical unit, that is to say that it has a left and a
right stereoscopic partial beam path, wherein each partial beam
path has its own optical elements. As an alternative, however, the
magnification setting unit can also be embodied as a so-called
"large optical unit", that is to say that its optical elements are
so large that they are simultaneously permeated by both
stereoscopic partial beam paths.
The magnification setting unit 25 is then followed by a purely
optical or an optical/electronic binocular tube 27. In a purely
optical binocular tube 27, a tube objective and an eyepiece are
arranged in each stereoscopic partial beam path. By means of the
tube objectives, intermediate images are respectively generated in
the stereoscopic partial beam paths, said intermediate images being
imaged toward infinity by means of the eyepiece optical unit, such
that an observer can observe the intermediate images with a relaxed
eye. In a combined optical and electronic binocular tube 27, each
stereoscopic partial beam path contains an imaging optical unit
that images the observation object 23 onto two electronic image
sensors.
In the present exemplary embodiment, the illumination device of the
surgical microscope is embodied as so-called Kohler illumination.
In such illumination, the light source, that is to say the image 7
of the light emitting diode 3, is imaged into an intermediate image
plane, in which, in general, an aperture diaphragm 29 is situated,
with the aid of which the brightness of the illumination can be set
in a targeted manner. A luminous field diaphragm 31 is furthermore
present, which is situated in the observation beam path in a
conjugate plane with respect to the object plane of the observation
object 23. Objects arranged in such a conjugate plane are sharply
imaged in the object plane. By means of the luminous field
diaphragm 31, therefore, it is possible to realize a sharp
delimitation of the luminous field in the object. Overall, with a
Kohler optical unit, it is possible to generate a sharply delimited
homogeneous luminous field in the object 23. The illumination
optical unit illustrated in FIG. 4 substantially corresponds to the
illumination optical unit described in DE 10 2006 013 761 A1 with
the difference that, instead of the optical fiber exit end
described therein, the image 7 of the light emitting diode 3 serves
as a light source.
FIG. 5 shows a modification of the surgical microscope illustrated
in FIG. 4, in a plan view. The exemplary embodiment illustrated in
FIG. 5 differs from the exemplary embodiment illustrated in FIG. 1
both in terms of the light source arrangement 201 and in terms of
the illumination optical unit 215 in that it is embodied for
realizing a coaxial illumination. In such a coaxial illumination,
the illumination comprises two partial illumination beam paths,
which are fed to the object by means of a beam splitter 221
coaxially with respect to the stereoscopic partial observation beam
paths.
In the exemplary embodiment illustrated in FIG. 5, the light source
arrangement 201, for generating the coaxial illumination comprises
two luminescence emitters, namely two light emitting diodes 203A,
203B, and also a double collector 205 having two converging lenses
207, 209, which are embodied as large lenses, that is to say that
the lenses are permeated both by the light emerging from the light
emitting diode 203A and by the light emerging from the light
emitting diode 203B, in order to generate images 207A, 207B of the
light emitting diodes. The lens surfaces are aspherical in order to
make it possible to generate the two images with the smallest
possible imaging aberrations. The distance between the two images
207A, 207B is enlarged like the luminous area and the emission
angle with the magnification scale of the imaging optical unit,
such that a suitable distance between the two images 207A, 207B can
be realized by suitable setting of the distance between the two
light emitting diodes 203A, 203B.
The illumination optical unit 215 is likewise embodied as a large
optical unit, that is to say that a common collector optical unit
217 and a common condenser optical unit 219 are in each case
present both for the beam path emerging from the image 207A and for
the beam path emerging from the image 207B. Only the aperture
diaphragm 229 situated in the intermediate image plane of the
illumination optical unit 215 and the luminous field diaphragm 231
situated in the conjugate plane with respect to the object plane
are equipped as double diaphragms, that is to say that they
respectively have a diaphragm opening for each partial beam path of
the illumination.
By means of the beam splitter 221 the two partial beam paths of the
observation optical unit are then deflected through the main
objective 213 in the direction of the observation object. Such
coaxial illumination is often employed in ophthalmological surgical
microscopes, for example, for the purpose of generating red
reflection illumination.
An alternative realization of the coaxial illumination is
illustrated in a plan view in FIG. 6. The illumination device 215
and also the beam splitter 221 and the main objective 213 do not
differ from the corresponding elements from FIG. 5 and are
therefore designated by the same reference signs as in FIG. 5.
The modification shown in FIG. 6 differs from the surgical
microscope illustrated in FIG. 5 in that, instead of a light source
arrangement 201 comprising two luminescence emitters 203A, 203B,
two light source arrangements 201A, 201B are employed, each
comprising a single luminescence emitter 203A, 203B in the form of
light emitting diodes. Each luminescence emitter 203A, 203B is
assigned a dedicated imaging optical unit 205A, 205B, which in each
case corresponds to the imaging optical unit 105 shown in FIG.
4.
In the exemplary embodiment illustrated, the two light source
arrangements 201A, 201B are arranged opposite one another at an
angle of 90.degree. with respect to the optical axis of the
illumination optical unit 215, that is to say that the optical axes
of the double collectors 205A, 205B of the two light source
arrangements 201A, 201B are at an angle of 90.degree. with respect
to the optical axis of the illumination optical unit 215. By means
of a triangular mirror 233, the two radiation beams of the light
source arrangements are deflected by 90.degree. in order that the
images 207A, 207B of the light emitting diodes 203A, 203B, can be
coupled into the illumination optical unit 215.
Although the optical axes of the light source arrangements 201A,
201B in FIG. 6 are at an angle of 90.degree. with respect to the
optical axis of the illumination optical unit 215, the light source
arrangements 201A, 201B can also be arranged at a different angle
relative to the optical axis of the illumination optical unit 215.
The angle of the triangular mirror 233 should then be adapted
accordingly.
While the variant illustrated in FIG. 5 with a single light source
arrangement comprising two light emitting diodes affords the
advantage that only a single double collector has to be present,
the variant illustrated in FIG. 6 affords the possibility of using
standard light emitting diodes in each light source arrangement
201A, 201B. In the variant illustrated in FIG. 5, by contrast,
under certain circumstances, a special production of the two LEDs
203A, 203B is necessary in order to bring their luminous areas
close enough to one another in order that the distance between the
images 207A, 207B does not become too large for the desired
application.
The invention has been described on the basis of specific exemplary
embodiments for explanation purposes. However, it is possible to
depart from these exemplary embodiments. Thus, mirrors or prisms
can be present between the two lenses of the double collector, for
example, in order to fold the beam path. The structural length of
the light source arrangement can thereby be shortened.
The light source arrangement according to the invention makes it
possible to use luminescence emitters such as, in particular, light
emitting diodes, but also organic light emitting diodes or
luminescence films, provided that the intensity thereof is high
enough, instead of incandescent lamps or gas discharge lamps as
primary light sources. Through a suitable choice of the imaging
optical unit it is possible to generate images of the luminescence
emitters which can then be used as an illumination light source of
the illumination optical unit in a medical-optical observation
apparatus. By comparison with the use of incandescent lamps or gas
discharge lamps, this results in price advantages and also a longer
service life. The light source arrangement according to the
invention affords more homogeneous light propagation by comparison
with the output ends of optical fibers as illumination light
sources.
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